Edwards syndrome
435802
224764602
2008-07-10T09:15:56Z
84.48.60.203
{{Citations missing|date=August 2007}}
{{Infobox_Disease |
Name = Trisomy 18 |
Image = Chromosome 18.svg |
Caption = [[Chromosome 18]] |
DiseasesDB = 13378 |
ICD10 = {{ICD10|Q|91|0|q|90}}-{{ICD10|Q|91|3|q|90}} |
ICD9 = {{ICD9|758.2}} |
ICDO = |
OMIM = |
MedlinePlus = |
eMedicineSubj = ped |
eMedicineTopic = 652 |
MeshID = |
}}
'''Trisomy 18''' or '''Edwards Syndrome''' (named after [[John H. Edwards]], who first described the syndrome in 1960) is a [[genetic disorder]]. It is the most common [[autosome|autosomal]] [[trisomy]] after [[Down Syndrome]] that carries to term.
It is caused by a trisomy 18, which is the presence of three — as opposed to two — copies of [[Chromosome 18 (human)|chromosome 18]] in a fetus or infant's cells.
The additional chromosome usually occurs before [[Fertilisation|conception]]. A healthy egg or sperm cell contains individual chromosomes - one to contribute to each of the 23 pairs of chromosomes needed to form a normal cell with 46 chromosomes. Numerical errors arise at either of the two meiotic divisions and cause the failure of segregation of a chromosome into the daughter cells (non-disjunction). This results in an extra chromosome making the haploid number 24 rather than 23. Fertilization of these eggs or sperm that contain an extra chromosome results in trisomy, or three copies of a chromosome rather than two.
==Prognosis==
The survival rate of Edwards Syndrome is very low. About half die in utero. Of liveborn infants, only 50% live to 2 months, and only 5–10% will survive their first year of life. Major causes of death include [[apnea]] and heart abnormalities. It is impossible to predict the exact [[prognosis]] of an Edwards Syndrome child during [[pregnancy]] or the [[Neonate|neonatal period]]. Because major medical interventions are routinely withheld from these children, it is difficult to determine what the survival rate or prognosis would be with aggressive medical treatment.
==Incidence/prevalence==
The rate of occurrence for Edwards Syndrome is approximately one in 3,000 (for conception) and approximately one in 6,000 (for live births), as 50% of those diagnosed prenatally with the condition will not survive the prenatal period. Although women in their 20s and 30s may conceive Edwards Syndrome babies, there is an increased risk of conceiving a child with Edwards Syndrome as a woman's age increases, with the average age for this disorder being 32½.<ref>{{cite web |url=http://www.wrongdiagnosis.com/e/edwards_syndrome/prevalence.htm |title=Prevalence and Incidence of Edwards Syndrome |accessdate=2008-02-17 |date=2008-02-04 |work=Diseases Center-Edwards Syndrome |publisher=Adviware Pty Ltd. |quote=mean maternal age for this disorder is 32½}}</ref>
==Variations==
A small percentage of cases occur when only some of the body's cells have an extra copy of chromosome 18, resulting in a mixed population of cells with a differing number of chromosomes. Such cases are sometimes called [[Mosaic (genetics)|mosaic]] Edwards syndrome. Very rarely, a piece of chromosome 18 becomes attached to another chromosome ([[Chromosomal translocation|translocated]]) before or after conception. Affected people have two copies of chromosome 18, plus extra material from chromosome 18 attached to another chromosome. With a translocation, the person has a partial trisomy for chromosome 18 and the abnormalities are often less than for the typical Edwards syndrome.
==Features and characteristics==
Symptoms and findings may be extremely variable from case to case. However, in many affected infants, the following may be found:
* [[Arthrogryposis]] (a muscle disorder that causes multiple joint contractures at birth)
* [[Growth deficiency]]
* [[Feeding difficulties]]
* [[Breathing difficulties]]
* [[Developmental delays]]
* [[Mental retardation]]
* [[Undescended testicles]] in [[males]]
* Prominent back portion of the [[head]] (occiput)
* Small head ([[microcephaly]])
* Low-set, [[malformed ears]]
* Abnormally small jaw ([[micrognathia]])
* [[Small mouth]]
* [[Cleft lip]]/[[Cleft palate]]
* [[Upturned nose]]
* Narrow eyelid folds ([[palpebral fissures]])
* Widely-spaced eyes ([[ocular hypertelorism]])
* Drooping of the upper eyelids ([[ptosis (eyelid)|ptosis]])
* Overlapped, flexed [[finger]]s
* Underdeveloped or [[absent thumbs]]
* [[Underdeveloped nails]]
* [[Absent radius]]
* [[Webbed toes|Webbing]] of the second and third [[toes]]
* [[Clubfoot]] or ''Rocker bottom feet''
* [[Small pelvis]] with limited movements of the [[Hip (anatomy)|hips]]
* [[Short breastbone]]
* [[Kidney malformations]]
* Structural heart defects at birth (i.e., [[ventricular septal defect]], [[atrial septal defect]], [[patent ductus arteriosus]])
* Intestines protruding outside the body ([[omphalocele]])
==References==
{{reflist}}
{{refbegin}}
*Stenson, Carol M. (1999). ''Trisomy 18: A Guidebook for Families''. University of Nebraska Medical Center. ISBN 1-889843-29-6.
*Barnes, Ann M. (2000). ''Care of the infant and child with trisomy 18 or 13: medical problems, reported treatments and milestones''. University of Nebraska Medical Center. ISBN 1-889843-58-X.
{{refend}}
*[http://www.trisomy18.org Trisomy 18 Foundation, Inc.]
*[http://www.trisomy18support.org Trisomy 18 Support Program]
*[http://www.trisomy.org Support Organisation For Trisomy 18, 13, and Related Disorders] (SOFT)
*[http://www.chromosome18.org The Chromosome 18 Registry & Research Society]
*[http://video.on.nytimes.com/?fr_story=79cf26acead199fa0a000074e41deda20072c923 „Perinatal Hospice Care - Preparing for birth and death”]
* {{WhoNamedIt|synd|3438}}
{{Chromosomal abnormalities}}
[[Category:Genetic disorders]]
[[Category:Syndromes]]
[[cs:Edwardsův syndrom]]
[[da:Edwards syndrom]]
[[de:Edwards-Syndrom]]
[[et:Edwardsi sündroom]]
[[es:Síndrome de Edwards]]
[[fr:Trisomie 18]]
[[it:Sindrome di Edwards]]
[[ko:에드워드 증후군]]
[[lt:Edvardso sindromas]]
[[nl:Syndroom van Edwards]]
[[ja:エドワード症候群]]
[[no:Edwards syndrom]]
[[pl:Zespół Edwardsa]]
[[pt:Síndrome de Edwards]]
[[ru:Синдром Эдвардса]]
[[sr:Едвардсов синдром]]
[[fi:Edwardsin oireyhtymä]]
[[sv:Edwards syndrom]]
[[tr:Edwards sendromu]]
[[uk:Синдром Едвардса]]
[[zh:愛德華氏症候群]]